To provide a flow pattern forming body in which the inside diameter of a passage can be made into a small one as it could not be obtained by a conventional boring however long the passage to be formed is, the residual oil within the passage can be removed, and a passage of a desired pattern can be formed, and also a passage device capable of easily and precisely regulating the temperature of a gas carried within a passage.

In this device 100, a plurality of narrow pipes 11, 12, 13 are mutually connected by a joint block 14 to constitute a flow pattern forming body 10. The joint block 14 has fine holes 15, 16, 17 mutually allowing in the inner parts, and the narrow pipes 11, 12, 13 are inserted to the fine holes 15, 16, 17, whereby a flow pattern F' is formed. The flow pattern forming body 10 is put in a block 20 made of aluminum excellent in heat conductivity.